Late effects after ablative allogeneic stem cell transplantation for adolescent and young adult acute myeloid leukemia

International recommendations for screening and preventative practices for long-term survivors of transplantation and cellular therapy: a 2023 update

As hematopoietic cell transplantation (HCT) and cellular therapy expand to new indications and international access improves, the volume of HCT performed annually continues to rise. Parallel improvements in HCT techniques and supportive care entails more patients surviving long-term, creating further emphasis on survivorship needs. Survivors are at risk for developing late complications secondary to pre-, peri- and post-transplant exposures and other underlying risk-factors. Guidelines for screening and preventive practices for HCT survivors were originally published in 2006 and updated in 2012. To review contemporary literature and update the recommendations while considering the changing practice of HCT and cellular therapy, an international group of experts was again convened. This review provides updated pediatric and adult survivorship guidelines for HCT and cellular therapy. The contributory role of chronic graft-versus-host disease (cGVHD) to the development of late effects is discussed but cGVHD management is not covered in detail. These guidelines emphasize special needs of patients with distinct underlying HCT indications or comorbidities (e.g., hemoglobinopathies, older adults) but do not replace more detailed group, disease, or condition specific guidelines. Although these recommendations should be applicable to the vast majority of HCT recipients, resource constraints may limit their implementation in some settings.

Cardiovascular Management of Patients Undergoing Hematopoietic Stem Cell Transplantation: From Pretransplantation to Survivorship: A Scientific Statement From the American Heart Association

Hematopoietic stem cell transplantation can cure various disorders but poses cardiovascular risks, especially for elderly patients and those with cardiovascular diseases. Cardiovascular evaluations are crucial in pretransplantation assessments, but guidelines are lacking. This American Heart Association scientific statement summarizes the data on transplantation-related complications and provides guidance for the cardiovascular management throughout transplantation. Hematopoietic stem cell transplantation consists of 4 phases: pretransplantation workup, conditioning therapy and infusion, immediate posttransplantation period, and long-term survivorship. Complications can occur during each phase, with long-term survivors facing increased risks for late effects such as cardiovascular disease, secondary malignancies, and endocrinopathies. In adults, arrhythmias such as atrial fibrillation and flutter are the most frequent acute cardiovascular complication. Acute heart failure has an incidence ranging from 0.4% to 2.2%. In pediatric patients, left ventricular systolic dysfunction and pericardial effusion are the most common cardiovascular complications. Factors influencing the incidence and risk of complications include pretransplantation therapies, transplantation type (autologous versus allogeneic), conditioning regimen, comorbid conditions, and patient age. The pretransplantation cardiovascular evaluation consists of 4 steps: (1) initial risk stratification, (2) exclusion of high-risk cardiovascular disease, (3) assessment of cardiac reserve, and (4) optimization of cardiovascular reserve. Clinical risk scores could be useful tools for the risk stratification of adult patients. Long-term cardiovascular management of hematopoietic stem cell transplantation survivors includes optimizing risk factors, monitoring, and maintaining a low threshold for evaluating cardiovascular causes of symptoms. Future research should prioritize refining risk stratification and creating evidence-based guidelines and strategies to optimize outcomes in this growing patient population.

International Recommendations for Screening and Preventative Practices for Long-Term Survivors of Transplantation and Cellular Therapy: A 2023 Update

As hematopoietic cell transplantation (HCT) and cellular therapy expand to new indications and international access improves, the number of HCTs performed annually continues to rise. Parallel improvements in HCT techniques and supportive care entails more patients surviving long term, creating further emphasis on survivorship needs. Survivors are at risk for developing late complications secondary to pretransplantation, peritransplantation, and post-transplantation exposures and other underlying risk factors. Guidelines for screening and preventive practices for HCT survivors were originally published in 2006 and then updated in 2012. An international group of experts was convened to review the contemporary literature and update the recommendations while considering the changing practices of HCT and cellular therapy. This review provides updated pediatric and adult survivorship guidelines for HCT and cellular therapy. The contributory role of chronic graft-versus-host disease (cGVHD) to the development of late effects is discussed, but cGVHD management is not covered in detail. These guidelines emphasize the special needs of patients with distinct underlying HCT indications or comorbidities (eg, hemoglobinopathies, older adults) but do not replace more detailed group-, disease-, or condition-specific guidelines. Although these recommendations should be applicable to the vast majority of HCT recipients, resource constraints may limit their implementation in some settings.

Severity of Chronic Graft-versus-Host Disease and Late Effects Following Allogeneic Hematopoietic Cell Transplantation for Adults with Hematologic Malignancy

The study aimed to determine the association of chronic graft-versus-host disease (cGVHD) diagnosis and severity with the development of subsequent neoplasms (SN) and nonmalignant late effects (NM-LE) in 2-year disease-free adult survivors following hematopoietic cell transplantation (HCT) for a hematologic malignancy. To do so, we conducted a retrospective analysis of 3884 survivors of HCT for hematologic malignancy in the Center of International Blood and Marrow Transplant Research database. We conducted a landmark analysis at the 2-year post-transplantation date, comparing first SN and NM-LE in survivors with and without cGVHD. The cumulative incidence (CuI) of SN and NM-LE were estimated through 10 years post-HCT in both groups, with death or disease relapse as a competing risk. Cox proportional hazards models were used to evaluate the associations of cGVHD and its related characteristics with the development of SN and NM-LE. The estimated 10-year CuI of SN in patients with GVHD (n = 2669) and patients without cGVHD (n = 1215) was 15% (95% confidence interval [CI], 14% to 17%) versus 9% (7.2% to 11%) (P < .001). cGVHD by 2 years post-HCT was independently associated with SN (hazard ratio [HR], 1.94; 95% CI, 1.53 to 2.46; P < .0001) with a standardized incidence ratio of 3.2 (95% CI, 2.9 to 3.5; P < .0001). Increasing severity of cGVHD was associated with an increased risk of SN. The estimated 10-year CuI of first NM-LE in patients with and without cGVHD was 28 (95% CI, 26% to 30%) versus 13% (95% CI, 11% to 15%) (P < .001). cGVHD by 2 years post-HCT was independently associated with NM-LE (HR, 2.23; 95% CI, 1.81 to 2.76; P < .0001). Multivariate analysis of cGVHD-related factors showed that increasing severity of cGVHD, extensive grade, having both mucocutaneous and visceral involvement, and receiving cGVHD treatment for >12 months were associated with the greatest magnitude of risk for NM-LE. cGVHD was closely associated with both SN and NM-LE in adult survivors of HCT for hematologic malignancy. Patients identified as having more severe involvement and both mucocutaneous and visceral organ involvement may warrant enhanced monitoring and screening for SNs and NM-LEs. However, caution is warranted when interpreting these results, as patients with cGVHD may have more vigilant post-transplantation health care and surveillance for late effects.

Low-dose anti-thymocyte globulin plus low-dose post-transplant cyclophosphamide-based regimen for prevention of graft-versus-host disease after haploidentical peripheral blood stem cell transplants: a large sample, long-term follow-up retrospective study

Introduction

The novel low-dose anti-thymocyte (ATG, 5 mg/kg) plus low-dose post-transplant cyclophosphamide (PTCy, 50 mg/kg) (low-dose ATG/PTCy)-based regimen had promising activity for prevention of graft-versus-host disease (GVHD) in haploidentical-peripheral blood stem cell transplantation (haplo-PBSCT), but its impacts on long-term outcomes remain to be defined.

Methods

We performed a large sample, long-term follow-up retrospective study to evaluate its efficacy for GVHD prophylaxis.

Results

The study enrolled 260 patients, including 162 with myeloid malignancies and 98 with lymphoid malignancies. The median follow-up time was 27.0 months. For the entire cohort, the cumulative incidences (CIs) of grade II-IV and III-IV acute GVHD (aGVHD) by 180 days were 13.46% (95% CI, 9.64%-17.92%) and 5.77% (95% CI, 3.37%-9.07%); while total and moderate/severe chronic GVHD (cGVHD) by 2 years were 30.97% (95% CI, 25.43%-36.66%) and 18.08% (95% CI, 13.68%-22.98%), respectively. The 2-year overall survival (OS), relapse-free survival (RFS), GVHD-free, relapse-free survival (GRFS), non-relapse mortality (NRM), and CIs of relapse were 60.7% (95% CI, 54.8%-67.10%), 58.1% (95% CI, 52.2%-64.5%), 50.6% (95% CI, 44.8-57.1%), 23.04% (95% CI, 18.06%-28.40%), and 18.09% (95% CI, 14.33%-23.97%, respectively. The 1-year CIs of cytomegalovirus (CMV) and Epstein-Barr virus (EBV) reactivation were 43.46% (95% CI, 37.39%-49.37%) and 18.08% (95% CI, 13.68%-22.98%), respectively. In multivariate analysis, the disease status at transplantation was associated with inferior survivor outcomes for all patients and myeloid and lymphoid malignancies, while cGVHD had superior outcomes for all patients and myeloid malignancies, but not for lymphoid malignancies.

Discussion

The results demonstrated that the novel regimen could effectively prevent the occurrence of aGVHD in haplo-PBSCT.

Cardiovascular morbidity following conventional therapy versus allogeneic hematopoietic stem cell transplantation after childhood, adolescent, and young adult leukemia in Finland

Allogeneic hematopoietic stem cell transplantation (aHSCT) represents a therapeutic choice for high-risk and relapsed leukemia at a young age. In this retrospective population-based study, we evaluated cardiovascular complications after aHSCT (N = 272) vs conventional therapy (N = 1098) among patients diagnosed with acute lymphoblastic or acute myeloid leukemia below 35 years between 1985 and 2004. Additionally, siblings from a prior comparison group served as population controls (N = 39 217). Childhood leukemia and aHSCT was associated with a 16-fold HR for developing arterial hypertension (HR 16.8, 95%CI 1.5-185.5) compared with conventional therapy. A 2-fold HR for any cardiovascular complication was observed after AYA leukemia and aHSCT vs conventional treatment (HR 2.7, 95% CI 1.4-5.1). After AYA leukemia and aHSCT, the HR of cardiac arrhythmia was significantly elevated vs conventional therapy (HR 14.4, 95% CI 1.5-125.2). Moreover, after aHSCT in childhood, elevated hazard ratios (HRs) were found for cardiomyopathy/ cardiac insufficiency (HR 105.0, 95% CI 10.0-1100.0), cardiac arrhythmia, and arterial hypertension (HR 20.1, 95%CI 2.5-159.7 and HR 20.0, 95%CI 4.1-97.4) compared with healthy controls. After adolescent and young adult (AYA) leukemia and aHSCT, markedly increased HRs were observed for cardiac arrhythmia (HR 29.2, 95%CI 6.6-129.2), brain vascular thrombosis/ atherosclerosis and cardiomyopathy/cardiac insufficiency (HR 23.4, 95%CI 7.1-77.4 and HR 19.2, 95%CI 1.5-245.2) compared with healthy controls. As the cumulative incidence for cardiovascular complications rose during the follow-up of childhood and AYA leukemia patients, long-term cardiovascular surveillance is warranted to optimize the quality of life after childhood and AYA leukemia following both conventional treatment and aHSCT.

Chronic conditions, late mortality, and health status after childhood AML: a Childhood Cancer Survivor Study report

Five-year survival following childhood acute myeloid leukemia (AML) has increased following improvements in treatment and supportive care. Long-term health outcomes are unknown. To address this, cumulative incidence of late mortality and grades 3 to 5 chronic health condition (CHC) were estimated among 5-year AML survivors diagnosed between 1970 and 1999. Survivors were compared by treatment group (hematopoietic cell transplantation [HCT], chemotherapy with cranial radiation [chemo + CRT], chemotherapy only [chemo-only]), and diagnosis decade. Self-reported health status was compared across treatments, diagnosis decade, and with siblings. Among 856 survivors (median diagnosis age, 7.1 years; median age at last follow-up, 29.4 years), 20-year late mortality cumulative incidence was highest after HCT (13.9%; 95% confidence interval [CI], 10.0%-17.8%; chemo + CRT, 7.6%; 95% CI, 2.2%-13.1%; chemo-only, 5.1%; 95% CI, 2.8%-7.4%). Cumulative incidence of mortality for HCT survivors diagnosed in the 1990s (8.5%; 95% CI, 4.1%-12.8%) was lower vs those diagnosed in the 1970s (38.9%; 95% CI, 16.4%-61.4%). Most survivors did not experience any grade 3 to 5 CHC after 20 years (HCT, 45.8%; chemo + CRT, 23.7%; chemo-only, 27.0%). Furthermore, a temporal reduction in CHC cumulative incidence was seen after HCT (1970s, 76.1%; 1990s, 38.3%; P = .02), mirroring reduced use of total body irradiation. Self-reported health status was good to excellent for 88.2% of survivors; however, this was lower than that for siblings (94.8%; P < .0001). Although HCT is associated with greater long-term morbidity and mortality than chemotherapy-based treatment, gaps have narrowed, and all treatment groups report favorable health status.

Outcomes after allogeneic haematopoietic stem cell transplantation in young adults in Germany

Young adults (YA) represent a minority among recipients of allogeneic haematopoietic stem cell transplantation (HSCT). In order to describe the outcome of YA following HSCT in Germany, 9299 patients who were registered with the German Registry for Stem Cell Transplantation were included in this retrospective analysis of the years 1998-2019. The impact of the variables, such as patient age and sex, sex differences, stem cell source, donor type, conditioning, year of HSCT, the diagnosis, and the achieved remission status were tested in univariable and multivariable analysis for overall, event-free and relapse-free survival as well as for the cumulative incidences of non-relapse and therapy-related mortality. Altogether, the outcome of YA after HSCT improved over time and was determined by the underlying disease, the age at disease onset, stem cell source, and donor type. Patients were most likely to die from relapse, and survival of HSCT recipients after 10 years was reduced by more than half in comparison to the general population of YA. Deeper understanding of modifiable risk factors may be gained by studies comparing the outcome of YA post-HSCT with that of children, adolescents and elderly patients. A deliberate and strong patient selection may further improve mortality rates.

Outcomes of allogeneic haematopoietic stem cell transplantation with intensity-modulated total body irradiation by helical tomotherapy: a 2-year prospective follow-up study

BACKGROUND AND OBJECTIVES

Intensity-modulated radiation therapy (IMRT) helps achieve good radiation dose conformity and precise dose evaluation. We conducted a single-centre prospective study to assess the safety and feasibility of total body irradiation with IMRT (IMRT-TBI) using helical tomotherapy in allogeneic haematopoietic stem cell transplantation (allo-HSCT).

PATIENTS AND METHODS

Thirty-nine adult patients with haematological malignancy (acute lymphoblastic leukaemia [n = 21], chronic myeloid leukaemia [n = 6], mixed phenotype acute leukaemia [n = 5], acute myeloid leukaemia [n = 4], and malignant lymphoma [n = 3]) who received 12 Gy IMRT-TBI were enrolled with a median follow-up of 934.5 (range, 617-1254) d. At the time of transplantation, 33 patients (85%) achieved complete remission. The conditioning regimen used IMRT-TBI (12 Gy in 6 fractions twice daily, for 3 d) and cyclophosphamide (60 mg/kg/d, for 2 d), seven patients were combined with cytarabine, and five with etoposide. We set dose constraints for the lungs, kidneys and lens as the organs at risk.

RESULTS

The mean doses for the lungs and kidneys were 7.50 and 9.11 Gy, respectively. The mean maximum dose for the lens (right/left) was 5.75/5.87 Gy. The 2-year overall survival (OS), disease-free survival (DFS), cumulative incidence of relapse (CIR) and non-relapse mortality (NRM) were 69, 64, 18 and 18%, respectively. Thirty-six patients developed early adverse events (AEs) (including four patients with Grade 3/4 toxicities), most of which were reversible oral mucositis and may partially have been related to IMRT-TBI. However, the incidence of toxicity was comparable to conventional TBI-based conditioning transplantation. None of the patients developed primary graft failure, or Grade III-IV acute graft-versus-host disease (GVHD). In late complications, chronic kidney disease was observed in six patients, a lower incidence compared to conventional TBI-based conditioning transplantation. No radiation pneumonitis or cataracts were observed in any of the patients.

CONCLUSIONS

IMRT-TBI is safe and feasible for haematological malignancies with acceptable clinical outcomes.KEY MESSAGESIMRT-TBI-helical tomotherapy aids in accurate dose calculation and conformity.It could be used without any considerable increase in the rate of TBI-related AEs.Allo-HSCT with IMRT-TBI may be an alternative to conventional TBI for clinical use.

Adolescents and young adults (AYA) with acute myeloid leukemia (AML): real-world long-term results and age-specific outcomes

Opposing acute lymphoblastic leukemia, sparse data about AYAs with acute myeloid leukemia (AML) is available. Overall, 125 AYAs (age 10-35 years) treated during the last two decades were evaluated and compared to 385 older patients. CBF leukemia was more frequent in AYAs (21.6% vs. 8%, p < 0.001); however, many presented high-risk features. AYAs showed improved complete remission rate (CR, 80% vs. 65%, p = 0.01), lower cumulative incidence of relapse and TRM and longer survival (5 year-OS 53% vs. 24%, p < 0.0001), observed mainly in intermediate-risk karyotype. Adolescents displayed even better outcomes (5 year-OS 69%). AlloHCT in CR1 was beneficial for nonadolescent AYAs (5 year-OS 66.7% vs. 44.4% without HCT, p = 0.04). Among 50 APL patients, 19 AYAs experienced better outcomes than older, mainly attributed to reduced treatment-related mortality (TRM, 5% vs. 19%, p = 0.1). We observed an important (>10%) survival gain for AYAs during the last decade. However, AYAs have still unmet needs to obtain optimal cure rates.

Burden of Long-Term Morbidity Borne by Survivors of Acute Myeloid Leukemia Treated With Blood or Marrow Transplantation: The Results of the BMT Survivor Study

PURPOSE

Blood or marrow transplantation (BMT) is an integral part of consolidation and/or salvage therapy for patients with acute myeloid leukemia (AML). With the growing population of AML survivors, there is a need to understand the quality of their survival.

MATERIALS AND METHODS

This multisite study included 1,369 2-year survivors who underwent BMT for AML between 1974 and 2014 at age ≥ 21 years and 1,310 siblings. Using Common Terminology Criteria for Adverse Events, severe/life-threatening and fatal chronic health conditions were identified. Multivariable regression analysis was used to compare the risk of severe/life-threatening conditions and health status between survivors and siblings, and to identify risk factors for health conditions among BMT survivors.

RESULTS

The prevalence of severe/life-threatening conditions was 54.9% in BMT survivors compared with 28.5% in siblings (P < .001), yielding 3.8-fold higher odds of severe/life-threatening conditions (95% CI, 3.1 to 4.7) among the BMT survivors. The most prevalent conditions included subsequent neoplasms, diabetes, cataracts, venous thromboembolism, and joint replacement. Survivors were more likely to report poor general health (odds ratio [OR], 3.8; 95% CI, 2.8 to 5.1), activity limitation (OR, 3.7; 95% CI, 3.0 to 4.5), and functional impairment (OR, 2.9; 95% CI, 2.3 to 3.6). Among BMT recipients, the 20-year cumulative incidence of severe/life-threatening/fatal conditions was 68%. History of chronic graft-versus-host disease was associated with a higher risk of pulmonary disease (hazard ratio [HR], 3.1; 95% CI, 1.0 to 9.3), cataract (HR, 2.6; 95% CI, 1.4 to 3.8), and venous thromboembolism (HR, 2.3; 95% CI, 1.3 to 4.7). Relapse-related mortality (RRM) plateaued at 30%, whereas non-RRM increased to 50% at 30 years.

CONCLUSION

The burden of severe/life-threatening conditions is substantially higher in BMT recipients when compared with an unaffected comparison group, contributing to an increasing incidence of non-RRM over time. Chronic graft-versus-host disease was an important risk factor for severe/life-threatening/fatal conditions among BMT recipients, informing the need for close monitoring to anticipate and manage morbidity.

Association of Chronic Graft-versus-Host Disease with Late Effects following Allogeneic Hematopoietic Cell Transplantation for Children with Hematologic Malignancy

Chronic graft-versus-host disease (cGVHD) occurs in up to 25% of children following allogeneic hematopoietic cell transplantation (HCT) and continues to be a major cause of late morbidity and poor quality of life among long-term survivors of pediatric HCT. Late effects (LEs) of HCT are well documented in this population, and cGVHD has been identified as a risk factor for subsequent neoplasms (SNs) and several nonmalignant LEs (NM-LEs); however, the reported correlation between cGVHD and LEs varies among studies. We compared LEs occurring ≥2 years following childhood HCT for a hematologic malignancy in 2-year disease-free survivors with and without cGVHD and further evaluated the association of cGVHD features on the development of LEs. This systematic retrospective analysis used data from the Center of International Blood and Marrow Transplant Research (CIBMTR) on a large, representative cohort of 1260 survivors of pediatric HCT for hematologic malignancy to compare first malignant LEs and NM-LEs in those with a diagnosis of cGVHD and those who never developed cGVHD. The cumulative incidences of any first LE, SN, and NM-LE were estimated at 10 years after HCT, with death as a competing risk for patients with cGVHD versus no cGVHD. Cox proportional hazards models were used to evaluate the impact of cGVHD and its related characteristics on the development of first LEs. The estimated 10-year cumulative incidence of any LE in patients with and without cGVHD was 43% (95% CI, 38% to 48.2%) versus 32% (95% confidence interval [CI], 28.5% to 36.3%) (P < .001), respectively. The development of cGVHD by 2 years post-HCT was independently associated with any LE (hazard ratio [HR], 1.38; 95% CI, 1.13 to 1.68; P = .001) and NM-LE (HR, 1.37; 95% CI, 1.10 to 1.70; P = .006), but not SN (HR, 1.30; 95% CI, .73 to 2.31; P = .38). cGVHD-related factors linked with the development of an NM-LE included having extensive grade cGVHD (HR, 1.60; 95% CI, 1.23 to 2.08; P = .0005), severe cGVHD (HR, 2.25; 95% CI, 1.60 to 3.17; P < .0001), interrupted onset type (HR, 1.57; 95% CI, 1.21 to 2.05; P = .0008), and both mucocutaneous and visceral organ involvement (HR, 1.59; 95% CI, 1.24 to 2.03; P = .0002). No significant association between cGVHD-specific variables and SN was identified. Finally, the duration of cGVHD treatment of cGVHD with systemic immunosuppression was not significantly associated with SNs or NM-LEs. cGVHD was more closely associated with NM-LEs than with SNs among survivors of pediatric HCT for hematologic malignancy. In this analysis, the development of SNs was strongly associated with the use of myeloablative total body irradiation. cGVHD-related characteristics consistent with a state of greater immune dysregulation were more closely linked to NM-LEs.

Low-dose post-transplant cyclophosphamide with low-dose antithymocyte globulin for prevention of graft-versus-host disease in first complete remission undergoing 10/10 HLA-matched unrelated donor peripheral blood stem cell transplants: a multicentre, randomized controlled trial

The most widely used regimens of graft-versus-host disease (GVHD) prophylaxis in HLA-matched unrelated donor peripheral blood stem cell transplantation (MUD-PBSCT) are based on anti-thymocyte globulin (ATG) or post-transplant cyclophosphamide (PTCy). To improve the efficiency of GVHD prophylaxis, a novel regimen, composed of low-dose PTCy (20 mg/kg on day +3 and +4) and low-dose ATG (6 mg/kg), was evaluted in patients with hematological malignancies ungoing 10/10 HLA MUD-PBSCT in first remission (CR1). In our prospective, multicenter study, 104 patients were randomly assigned one-to-one to low-dose PTCy-ATG (n = 53) or standard-dose ATG (10 mg/kg, n = 51). Both the cumulative incidences (CIs) of grade II-IV acute GVHD (aGVHD) and chronic GVHD (cGVHD) at 2 years in low-dose PTCy-ATG cohort were significantly reduced (24.5% vs. 47.1%; P = 0.017; 14.1% vs. 33.3%; P = 0.013). The CI of non-relapse-mortality (NRM) was much lower (13.2% vs. 34.5%; P = 0.049) and GVHD-free, relapse-free survival (GRFS) was significantly improved at 2 years in low-dose PTCy-ATG arm (67.3% vs 42.3%; P = 0.032). The low-dose PTCy-ATG based GVHD prophylaxis is a promising strategy for patients in CR1 after 10/10 HLA MUD-PBSCT.

Long-Term Outcomes among Adolescent and Young Adult Survivors of Acute Leukemia: A Surveillance, Epidemiology, and End Results Analysis

BACKGROUND

There is a growing population of adolescent and young adult (AYA, age 15-39 years) acute leukemia survivors in whom long-term mortality outcomes are largely unknown.

METHODS

The current study utilized the Surveillance, Epidemiology, and End Results (SEER) registry to assess long-term outcomes of AYA acute leukemia 5-year survivors. The impact of diagnosis age, sex, race/ethnicity, socioeconomic status, and decade of diagnosis on long-term survival were assessed utilizing an accelerated failure time model.

RESULTS

A total of 1,938 AYA acute lymphoblastic leukemia (ALL) and 2,350 AYA acute myeloid leukemia (AML) survivors diagnosed between 1980 and 2009 were included with a median follow-up of 12.3 and 12.7 years, respectively. Ten-year survival for ALL and AML survivors was 87% and 89%, respectively, and 99% for the general population. Survival for AYA leukemia survivors remained below that of the age-adjusted general population at up to 30 years of follow-up. Primary cancer mortality was the most common cause of death in early survivorship with noncancer causes of death becoming more prevalent in later decades of follow-up. Male AML survivors had significantly worse survival than females (survival time ratio: 0.61, 95% confidence interval: 0.45-0.82).

CONCLUSIONS

AYA leukemia survivors have higher mortality rates than the general population that persist for decades after diagnosis.

IMPACT

While there have been improvements in late mortality, long-term survival for AYA leukemia survivors remains below that of the general population. Studies investigating risk factors for mortality and disparities in late effects among long-term AYA leukemia survivors are needed.

ESTRO ACROP and SIOPE recommendations for myeloablative Total Body Irradiation in children

BACKGROUND AND PURPOSE

Myeloablative Total Body Irradiation (TBI) is an important modality in conditioning for allogeneic hematopoietic stem cell transplantation (HSCT), especially in children with high-risk acute lymphoblastic leukemia (ALL). TBI practices are heterogeneous and institution-specific. Since TBI is associated with multiple late adverse effects, recommendations may help to standardize practices and improve the outcome versus toxicity ratio for children.

MATERIAL AND METHODS

The European Society for Paediatric Oncology (SIOPE) Radiotherapy TBI Working Group together with ESTRO experts conducted a literature search and evaluation regarding myeloablative TBI techniques and toxicities in children. Findings were discussed in bimonthly virtual meetings and consensus recommendations were established.

RESULTS

Myeloablative TBI in HSCT conditioning is mostly performed for high-risk ALL patients or patients with recurring hematologic malignancies. TBI is discouraged in children <3-4 years old because of increased toxicity risk. Publications regarding TBI are mostly retrospective studies with level III-IV evidence. Preferential TBI dose in children is 12-14.4 Gy in 1.6-2 Gy fractions b.i.d. Dose reduction should be considered for the lungs to <8 Gy, for the kidneys to ≤10 Gy, and for the lenses to <12 Gy, for dose rates ≥6 cGy/min. Highly conformal techniques i.e. TomoTherapy and VMAT TBI or Total Marrow (and/or Lymphoid) Irradiation as implemented in several centers, improve dose homogeneity and organ sparing, and should be evaluated in studies.

CONCLUSIONS

These ESTRO ACROP SIOPE recommendations provide expert consensus for conventional and highly conformal myeloablative TBI in children, as well as a supporting literature overview of TBI techniques and toxicities.

Long-term follow-up of patients with poor-risk acute leukemia treated on a phase 2 trial undergoing intensified conditioning regimen prior to allogeneic hematopoietic cell transplantation

Patients with acute leukemia who undergo allogenic hematopoietic cell transplantation with active disease have high rates of relapse and poor overall survival (OS) post-transplant compared to patients undergoing HCT in remission. Here, we report the long-term outcomes in 32 patients who received a high-intensity conditioning regimen comprising fractionated total body irradiation (FTBI; 1200 cGy) with pharmacokinetic (PK) dosing of intravenous Busulfan (IV BU) targeted to first dose area under curve (AUC) of 700-900 µM/min and etoposide (30 mg/kg) in a prospective phase 2 clinical trial. The median age of the patients at the time of HCT was 37 years (range: 18-50) presenting with high-risk (n = 6) and relapsed/refractory(r/r) acute leukemias (n = 26). All but one patient underwent HCT using peripheral blood stem cells from matched sibling donors. At a median follow-up of 17.3 years (range 14.4-19.0), 11 patients remained alive. The disease-free survival and OS at 15 years was 34% (versus 40% at 5-years post-HCT). The 15-year cumulative incidence of relapse was 26% and non-relapse mortality (NRM) was 38% (95% CI: 21-54%) and the cumulative incidence of chronic GVHD at 15 years was 33% using a prophylactic regimen of cyclosporine A and mycophenolate mofetil. The most common life-threatening late effects were secondary malignancies, metabolic, or cardiac complications with a cumulative incidence of 6.6%, 6.6%, and 13.3%, respectively. No unusual late effects or patterns of relapse were noted on longer followed on patients treated with intensified myeloablative condition regimen. Results from this study supports continued development of intensive conditioning regimens in patients with r/r acute leukemias to improve leukemia free (LFS) and OS in this high-risk population.

Total Body Irradiation in Haematopoietic Stem Cell Transplantation for Paediatric Acute Lymphoblastic Leukaemia: Review of the Literature and Future Directions

Total body irradiation (TBI) has been a pivotal component of the conditioning regimen for allogeneic myeloablative haematopoietic stem cell transplantation (HSCT) in very-high-risk acute lymphoblastic leukaemia (ALL) for decades, especially in children and young adults. The myeloablative conditioning regimen has two aims: (1) to eradicate leukaemic cells, and (2) to prevent rejection of the graft through suppression of the recipient's immune system. Radiotherapy has the advantage of achieving an adequate dose effect in sanctuary sites and in areas with poor blood supply. However, radiotherapy is subject to radiobiological trade-offs between ALL cell destruction, immune and haematopoietic stem cell survival, and various adverse effects in normal tissue. To diminish toxicity, a shift from single-fraction to fractionated TBI has taken place. However, HSCT and TBI are still associated with multiple late sequelae, leaving room for improvement. This review discusses the past developments of TBI and considerations for dose, fractionation and dose-rate, as well as issues regarding TBI setup performance, limitations and possibilities for improvement. TBI is typically delivered using conventional irradiation techniques and centres have locally developed heterogeneous treatment methods and ways to achieve reduced doses in several organs. There are, however, limitations in options to shield organs at risk without compromising the anti-leukaemic and immunosuppressive effects of conventional TBI. Technological improvements in radiotherapy planning and delivery with highly conformal TBI or total marrow irradiation (TMI), and total marrow and lymphoid irradiation (TMLI) have opened the way to investigate the potential reduction of radiotherapy-related toxicities without jeopardising efficacy. The demonstration of the superiority of TBI compared with chemotherapy-only conditioning regimens for event-free and overall survival in the randomised For Omitting Radiation Under Majority age (FORUM) trial in children with high-risk ALL makes exploration of the optimal use of TBI delivery mandatory. Standardisation and comprehensive reporting of conventional TBI techniques as well as cooperation between radiotherapy centres may help to increase the ratio between treatment outcomes and toxicity, and future studies must determine potential added benefit of innovative conformal techniques to ultimately improve quality of life for paediatric ALL patients receiving TBI-conditioned HSCT.

GSTM1 and GSTT1 double null genotypes determining cell fate and proliferation as potential risk factors of relapse in children with hematological malignancies after hematopoietic stem cell transplantation

PURPOSE

This study aimed to retrospectively evaluate the genetic association of null variants of glutathione S-transferases GSTM1 and GSTT1 with relapse incidence in children with hematological malignancies (HMs) undergoing busulfan (BU)- containing allogeneic hematopoietic stem cell transplantation (HSCT) and to assess the impact of these variants on BU-induced cytotoxicity on the immortalized lymphoblastoid cell lines (LCLs) and tumor THP1 GST gene-edited cell models.

METHODS

GSTM1- and GSTT1-null alleles were genotyped using germline DNA from whole blood prior to a conditioning BU-based regimen. Association of GSTM1- and GSTT1-null variants with relapse incidence was analyzed using multivariable competing risk analysis. BU-induced cell death studies were conducted in GSTs- null and non-null LCLs and CRISPR-Cas9 gene-edited THP1 leukemia cell lines.

RESULTS

Carrying GSTM1/GSTT1 double null genotype was found to be an independent risk factor for post-HSCT relapse in 86 children (adjusted HR: 6.52 [95% Cl, 2.76-15.42; p = 1.9 × 10^-5]). BU-induced cell death preferentially in THP1^{GSTM1(non-null)} and LCLs^{GSTM1(non-null)} as shown by decreased viability, increased necrosis and levels of the oxidized form of glutathione compared to null cells, while GSTT1 non-null cells showed increased baseline proliferation.

CONCLUSION

The clinical association suggests that GSTM1/GSTT1 double null genotype could serve as genetic stratification biomarker for the high risk of post-HSCT relapse. Functional studies have indicated that GSTM1 status modulates BU-induced cell death. On the other hand, GSTT1 is proposed to be involved in baseline cell proliferation.

Myeloablative Fractionated Busulfan With Fludarabine in Older Patients: Long Term Disease-Specific Outcomes of a Prospective Phase II Clinical Trial

Compared to reduced-intensity conditioning regimen, myeloablative conditioning (MAC) for hematopoietic stem cell transplantation (HCT) reduces relapse but is avoided in older patients because of higher non-relapse mortality (NRM). To meet the need for a myeloablative regimen for older patients, we developed a novel fludarabine and busulfan MAC regimen. We fractionated the dose of busulfan and gave it for 6 days over a 2-week period and demonstrated the feasibility and safety of this approach. However, the disease-specific efficacy of this regimen is not known. The purpose of this study was to estimate the efficacy of fractionated busulfan regimen by estimating diseases specific survival outcomes. The conditioning regimen consisted of busulfan and fludarabine. On days -13 and -12 before HCT, patients received 80 mg/m² busulfan intravenously (IV) daily in an outpatient clinic. Additional chemotherapy was administered during inpatient treatment from day -6 through day -3, including fludarabine 40 mg/m² and busulfan IV once daily. The dosing of busulfan was determined from pharmacokinetic analyses to achieve for the course a target area under the curve of 20,000 ± 12% μmol/min, which is close to the average exposure of myeloablative dose of busulfan. One hundred fifty patients with high-risk hematological malignancies up to 75 years were enrolled in this prospective phase II study. The objective was to evaluate NRM, relapse, survival, the rates of graft-versus-host disease (GVHD), and long-term complications. The median age of the patient population was 61 years (interquartile range, 55-67). The most common diagnoses were acute myeloid leukemia (AML; N = 59 [39.3%]), myelodysplastic syndrome (MDS; n = 29 [19.3%]), and myelofibrosis (MF; N = 22 [14.7%]). Most had an unrelated donor (n = 93 [62%]) and received peripheral blood graft (n = 110 [73.3%]). Over half had an HCT-specific comorbidity index of ≥3 (n = 79 [52.7%]). The median follow-up among survivors was 43.4 months (interquartile range, 38.9-50.4). In patients with AML in complete remission, MDS, and myelofibrosis, 3-year overall survival was 66.7% (95% confidence interval [CI], 50.2-88.5%), 43.6% (95% CI, 28.6-66.4%), and 59.1% (95% CI, 41.7-83.7%) respectively. The cumulative incidence of NRM was 22% (15.3%-28.7%), extensive chronic GVHD was 27% (95% CI, 20-34%), bronchiolitis obliterans was 4.7% (95% CI, 1.3-8.1%), and secondary malignancy was 8.7% (95% CI, 4.1-13.2%) at 3 years. Lengthening the duration of busulfan (fractionation) permits safe delivery of myeloablative conditioning in older patients, leading to prolonged survival. © 2021 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.

Comparison of total body irradiation versus non-total body irradiation containing regimens for de novo acute myeloid leukemia in children

With limited data comparing hematopoietic cell transplant outcomes between myeloablative total body irradiation (TBI) containing and non-TBI regimens in children with de novo acute myeloid leukemia, the aim of this study was to compare transplant-outcomes between these regimens. Cox regression models were used to compare transplant-outcomes after TBI and non-TBI regimens in 624 children transplanted between 2008 and 2016. Thirty two percent (n=199) received TBI regimens whereas 68% (n=425) received non-TBI regimens. Five-year non-relapse mortality was higher with TBI regimens (22% vs. 11%, P<0.0001) but relapse was lower (23% vs. 37%, P<0.0001) compared to non-TBI regimens. Consequently, overall (62% vs. 60%, P=1.00) and leukemia-free survival (55% vs. 52%, P=0.42) did not differ between treatment groups. Grade 2-3 acute graft versus host disease was higher with TBI regimens (56% vs. 27%, P<0.0001) but not chronic graft versus host disease. The 3-year incidence of gonadal or growth hormone deficiency was higher with TBI regimens (24% vs. 8%, P<0.001) but there were no differences in late pulmonary, cardiac or renal impairment. In the absence of a survival advantage, the choice of TBI or non-TBI regimen merits careful consideration with the data favoring non-TBI regimens to limit the burden of morbidity associated with endocrine dysfunction.

National Institutes of Health Consensus Development Project on Criteria for Clinical Trials in Chronic Graft-versus-Host Disease: IV. The 2020 Highly morbid forms report

Chronic graft-versus-host disease (GVHD) can be associated with significant morbidity, in part because of nonreversible fibrosis, which impacts physical functioning (eye, skin, lung manifestations) and mortality (lung, gastrointestinal manifestations). Progress in preventing severe morbidity and mortality associated with chronic GVHD is limited by a complex and incompletely understood disease biology and a lack of prognostic biomarkers. Likewise, treatment advances for highly morbid manifestations remain hindered by the absence of effective organ-specific approaches targeting "irreversible" fibrotic sequelae and difficulties in conducting clinical trials in a heterogeneous disease with small patient numbers. The purpose of this document is to identify current gaps, to outline a roadmap of research goals for highly morbid forms of chronic GVHD including advanced skin sclerosis, fasciitis, lung, ocular and gastrointestinal involvement, and to propose strategies for effective trial design. The working group made the following recommendations: (1) Phenotype chronic GVHD clinically and biologically in future cohorts, to describe the incidence, prognostic factors, mechanisms of organ damage, and clinical evolution of highly morbid conditions including long-term effects in children; (2) Conduct longitudinal multicenter studies with common definitions and research sample collections; (3) Develop new approaches for early identification and treatment of highly morbid forms of chronic GVHD, especially biologically targeted treatments, with a special focus on fibrotic changes; and (4) Establish primary endpoints for clinical trials addressing each highly morbid manifestation in relationship to the time point of intervention (early versus late). Alternative endpoints, such as lack of progression and improvement in physical functioning or quality of life, may be suitable for clinical trials in patients with highly morbid manifestations. Finally, new approaches for objective response assessment and exploration of novel trial designs for small populations are required.

Association Between Baseline Patient-Reported Outcomes and Complications of Hematopoietic Stem Cell Transplantation

Hematopoietic cell transplantation (HCT) is a potentially curative therapy for hematologic malignancies, but it often results in significant toxicities and impaired quality of life (QOL). Although the value of patient-reported outcomes (PROs) is increasingly recognized in HCT, data are limited regarding the relationship between PROs and HCT complications. We conducted a secondary data analysis of 250 patients who were hospitalized for autologous or allogeneic HCT at Massachusetts General Hospital from 2011 through 2016. We assessed QOL (Functional Assessment of Cancer Therapy-General), mood (Hospital Anxiety and Depression Scale), and fatigue (FACT-Fatigue) at baseline. We abstracted from the Electronic Health Record (1) hospitalization during the first 100 days after HCT, (2) days alive and out of the hospital in the first 100 days after HCT, and (3) cumulative incidence of acute graft-versus-host disease (GVHD) among allogeneic HCT recipients. We assessed the association of baseline PROs with HCT complications using multivariable models adjusting for patient and transplant characteristics. Overall, 44.4% (111/250) of patients underwent an autologous HCT, 25.2% (63/250) received a myeloablative allogeneic HCT, and 30.4% (76/250) underwent a reduced-intensity allogeneic HCT. In multivariable logistic regression, higher anxiety (odds ratio [OR] = 1.14, P = .004) was associated with higher likelihood of rehospitalization within 100 days after HCT. In multivariable Poisson regression, lower fatigue (β = 0.003, P = .015) was associated with increased days alive and out of the hospital in the first 100 days post-HCT. In multivariable logistic regression, lower baseline QOL (OR = 0.97, P = .034), higher fatigue (OR = 0.95, P = .004), and higher depression (OR = 1.15, P = .020) were associated with increased likelihood of acute GVHD. Baseline PROs are associated with health care utilization after HCT and risk of acute GVHD in allogeneic HCT recipients. These findings underscore the potential utility of pretransplantation PROs as important prognostic factors for HCT.

Cardiovascular disease and its management in children and adults undergoing hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation (HSCT) is a potentially curative treatment for many malignancies, hemoglobinopathies, metabolic diseases, bone marrow failure syndromes, and primary immune deficiencies. Despite the significant improvement in survival afforded by HSCT, the therapy is associated with major short and long-term morbidity and mortality. Cardiovascular complications such as cardiomyopathy, arrhythmias, pulmonary hypertension, and pericardial effusions are increasingly recognized as potential outcomes following HSCT. The incidence of cardiac complications is related to various factors such as age, co-morbid medical conditions, whether patients received cardiotoxic chemotherapy prior to HSCT, the type of HSCT (autologous versus allogeneic), and the specific conditioning regimen. Thus, the cardiovascular evaluation has become a core component of the pre-transplant assessment, however, the practice differs from center to center as national guidelines and contemporary high-quality studies are lacking. We review the incidence of cardiotoxicity in pediatric and adult HSCT, potential mechanisms of injury, and effects on long-term outcomes. We also discuss the possible therapeutic approaches when disease arises, as well as the indications and need for surveillance before, during, and after transplantation.

Allogeneic Hematopoietic Cell Transplantation for Adolescent and Young Adult Patients with Acute Myeloid Leukemia

Limited data exist regarding the outcomes of allogeneic hematopoietic cell transplantation (allo-HCT) among adolescent and young adult (AYA) patients with acute myeloid leukemia (AML). Here we analyzed the features and outcomes of AYA patients with AML who had achieved complete remission (CR) and those who had not (non-CR) at allo-HCT. We retrospectively analyzed 2350 AYA patients with AML who underwent allo-HCT with a myeloablative conditioning regimen and who were consecutively enrolled in the Japanese nationwide HCT registry. The difference in overall survival (OS) between younger (age 16 to 29 years) and older AYA (age 30 to 39 years) patients in CR at transplantation was not significant (70.2% versus 71.7% at 3 years; P = .62). Meanwhile, this difference trended toward a statistical significance between younger and older AYA patients in non-CR at transplantation (39.5% versus 34.3% at 3 years; P = .052). In AYA patients in CR and non-CR, the age at transplantation did not affect relapse or nonrelapse mortality (NRM). In AYA patients in CR, no difference in OS was observed between those who received total body irradiation (TBI) and those who did not (71.1% versus 70.5% at 3 years; P = .43). AYA patients who received TBI-based conditioning had a significantly lower relapse rate and higher NRM than those who underwent non-TBI-based conditioning (relapse: 19.8% versus 24.1% at 3 years [P = .047]; NRM: 14.7% versus 11.1% at 3 years [P = .021]). In contrast, among the non-CR patients, there were no differences between the TBI and non-TBI groups with respect to OS (P = .094), relapse (P = .83), and NRM (P = .27). Our data indicate that outcomes may be more favorable in younger AYA patients than in older AYA patients in non-CR at transplantation, and that outcomes of TBI-based conditioning could be comparable to those of non-TBI-based conditioning for AYA patients.

Beyond Premature Ovarian Insufficiency: Staging Reproductive Aging in Adolescent and Young Adult Cancer Survivors

CONTEXT

Although stages of reproductive aging for women in the general population are well described by STRAW+10 criteria, this is largely unknown for female adolescent and young adult cancer survivors (AYA survivors).

OBJECTIVE

This work aimed to evaluate applying STRAW + 10 criteria in AYA survivors using bleeding patterns with and without endocrine biomarkers, and to assess how cancer treatment gonadotoxicity is related to reproductive aging stage.

DESIGN

The sample (n = 338) included AYA survivors from the Reproductive Window Study cohort. Menstrual bleeding data and dried-blood spots for antimüllerian hormone (AMH) and follicle-stimulating hormone (FSH) measurements (Ansh DBS enzyme-linked immunosorbent assays) were used for reproductive aging stage assessment. Cancer treatment data were abstracted from medical records.

RESULTS

Among participants, mean age 34.0 ± 4.5 years and at a mean of 6.9 ± 4.6 years since cancer treatment, the most common cancers were lymphomas (31%), breast (23%), and thyroid (17%). Twenty-nine percent were unclassifiable by STRAW + 10 criteria, occurring more frequently in the first 2 years from treatment. Most unclassifiable survivors exhibited bleeding patterns consistent with the menopausal transition, but had reproductive phase AMH and/or FSH levels. For classifiable survivors (48% peak reproductive, 30% late reproductive, 12% early transition, 3% late transition, and 7% postmenopause), endocrine biomarkers distinguished among peak, early, and late stages within the reproductive and transition phases. Gonadotoxic treatments were associated with more advanced stages.

CONCLUSIONS

We demonstrate a novel association between gonadotoxic treatments and advanced stages of reproductive aging. Without endocrine biomarkers, bleeding pattern alone can misclassify AYA survivors into more or less advanced stages. Moreover, a large proportion of AYA survivors exhibited combinations of endocrine biomarkers and bleeding patterns that do not fit the STRAW + 10 criteria, suggesting the need for modified staging for this population.

A Review of Acute and Long-Term Neurological Complications Following Haematopoietic Stem Cell Transplant for Paediatric Acute Lymphoblastic Leukaemia

Despite advances in haematopoietic stem cell transplant (HSCT) techniques, the risk of serious side effects and complications still exists. Neurological complications, both acute and long term, are common following HSCT and contribute to significant morbidity and mortality. The aetiology of neurotoxicity includes infections and a wide variety of non-infectious causes such as drug toxicities, metabolic abnormalities, irradiation, vascular and immunologic events and the leukaemia itself. The majority of the literature on this subject is focussed on adults. The impact of the combination of neurotoxic drugs given before and during HSCT, radiotherapy and neurological complications on the developing and vulnerable paediatric and adolescent brain remains unclear. Moreover, the age-related sensitivity of the nervous system to toxic insults is still being investigated. In this article, we review current evidence regarding neurotoxicity following HSCT for acute lymphoblastic leukaemia in childhood. We focus on acute and long-term impacts. Understanding the aetiology and long-term sequelae of neurological complications in children is particularly important in the current era of immunotherapy for acute lymphoblastic leukaemia (such as chimeric antigen receptor T cells and bi-specific T-cell engager antibodies), which have well-known and common neurological side effects and may represent a future treatment modality for at least a fraction of HSCT-recipients.

Comorbidity profile of adult survivors at 20 years following allogeneic hematopoietic cell transplantation

Numerous chronic medical conditions and complications can arise following allogeneic hematopoietic cell transplantation (HCT) that may have a negative impact on survival and quality of life.

OBJECTIVE

The purpose of the present study was to review the comorbidities of a single-center cohort of allogeneic HCT recipients that survived 20 years postallogeneic transplantation.

METHODS

We retrospectively investigated 172 patients that underwent allogeneic HCT at the Princess Margaret Cancer Centre between 1979 and 1998 and who survived at least 20 years post-HCT.

RESULTS

The most frequent individual comorbidities documented were dyslipidemia (29%), hypertension (31%), osteoporosis (15%), hypothyroidism (15%), and depression/anxiety (13%). Follow-up data following the 20-year mark were available for 135 patients, overall survival (OS) of that group at 5 and 10 years was 94% and 90%, respectively. When grouped by the number of concurrent comorbidities, there was a significant difference in OS between the groups with 0-1, 2-3, and ≥4 comorbidities (P = .01).

CONCLUSIONS

Evidently, long-term allogeneic HCT recipients may develop a number of comorbidities that negatively influence survival even past the 20-year post-transplant mark. These findings warrant the continuous long-term medical follow-up of allogeneic transplant patients, regardless of age or time that has lapsed post-HCT.

Post-transplant cyclophosphamide versus antithymocyte globulin in patients with acute myeloid leukemia in first complete remission undergoing allogeneic stem cell transplantation from 10/10 HLA-matched unrelated donors

BACKGROUND

Graft-versus-host disease (GVHD) remains a major contributor to mortality and morbidity after allogeneic stem-cell transplantation (allo-HSCT). The updated recommendations suggest that rabbit antithymocyte globulin or anti-T-lymphocyte globulin (ATG) should be used for GVHD prophylaxis in patients undergoing matched-unrelated donor (MUD) allo-HSCT. More recently, using post-transplant cyclophosphamide (PTCY) in the haploidentical setting has resulted in low incidences of both acute (aGVHD) and chronic GVHD (cGVHD). Therefore, the aim of our study was to compare GVHD prophylaxis using either PTCY or ATG in patients with acute myeloid leukemia (AML) who underwent allo-HSCT in first remission (CR1) from a 10/10 HLA-MUD.

METHODS

Overall, 174 and 1452 patients from the EBMT registry receiving PTCY and ATG were included. Cumulative incidence of aGVHD and cGVHD, leukemia-free survival, overall survival, non-relapse mortality, cumulative incidence of relapse, and refined GVHD-free, relapse-free survival were compared between the 2 groups. Propensity score matching was also performed in order to confirm the results of the main analysis RESULTS: No statistical difference between the PTCY and ATG groups was observed for the incidence of grade II-IV aGVHD. The same held true for the incidence of cGVHD and for extensive cGVHD. In univariate and multivariate analyses, no statistical differences were observed for all other transplant outcomes. These results were also confirmed using matched-pair analysis.

CONCLUSION

These results highlight that, in the10/10 HLA-MUD setting, the use of PTCY for GVHD prophylaxis may provide similar outcomes to those obtained with ATG in patients with AML in CR1.

Minor Histocompatibility Antigen-Specific T Cells

Minor Histocompatibility (H) antigens are major histocompatibility complex (MHC)/Human Leukocyte Antigen (HLA)-bound peptides that differ between allogeneic hematopoietic stem cell transplantation (HCT) recipients and their donors as a result of genetic polymorphisms. Some minor H antigens can be used as therapeutic T cell targets to augment the graft-vs.-leukemia (GVL) effect in order to prevent or manage leukemia relapse after HCT. Graft engineering and post-HCT immunotherapies are being developed to optimize delivery of T cells specific for selected minor H antigens. These strategies have the potential to reduce relapse risk and thereby permit implementation of HCT approaches that are associated with less toxicity and fewer late effects, which is particularly important in the growing and developing pediatric patient. Most minor H antigens are expressed ubiquitously, including on epithelial tissues, and can be recognized by donor T cells following HCT, leading to graft-vs.-host disease (GVHD) as well as GVL. However, those minor H antigens that are expressed predominantly on hematopoietic cells can be targeted for selective GVL. Once full donor hematopoietic chimerism is achieved after HCT, hematopoietic-restricted minor H antigens are present only on residual recipient malignant hematopoietic cells, and these minor H antigens serve as tumor-specific antigens for donor T cells. Minor H antigen-specific T cells that are delivered as part of the donor hematopoietic stem cell graft at the time of HCT contribute to relapse prevention. However, in some cases the minor H antigen-specific T cells delivered with the graft may be quantitatively insufficient or become functionally impaired over time, leading to leukemia relapse. Following HCT, adoptive T cell immunotherapy can be used to treat or prevent relapse by delivering large numbers of donor T cells targeting hematopoietic-restricted minor H antigens. In this review, we discuss minor H antigens as T cell targets for augmenting the GVL effect in engineered HCT grafts and for post-HCT immunotherapy. We will highlight the importance of these developments for pediatric HCT.